The present invention relates generally to semiconductor wafer processing, and more particularly, to a technique for identifying the original location of a semiconductor chip on the wafer on which it was fabricated, even after the chip is separated from the wafer.
In semiconductor manufacturing, a multiplicity, e.g., 200, of individual semiconductor devices, e.g., memory devices such as SRAMs and DRAMs, are fabricated on a single semiconductor wafer. The semiconductor wafer is then sliced up into a corresponding multiplicity of individual dies or chips. Thus, each individual semiconductor device is often referred to as a semiconductor chip. The cost of manufacturing such semiconductor chips is a function of the ratio of non-defective chips/total chips fabricated on a given wafer, which is defined as wafer yield. Therefore, it is important to identify chip defects as early as possible in order to provide process control information which can be used to correct wafer processing problems at the earliest possible time, to thereby maximize product quality and throughput rate, and to minimize product manufacturing costs. In order to optimize process control, it is not only necessary to identify the existence of chip defects, but to also learn the nature and location of such defects so that corrective measures can be more specifically tailored to resolving the underlying wafer processing problem which led to such defect.
In this regard, it has heretofore been technically infeasible to determine the original location of a semiconductor chip on the wafer on which it was fabricated, after the chip has been separated from the wafer and packaged as a discrete product. Such information, if available, would provide more meaningful feedback to the wafer processing operation, and thus, would facilitate more precise troubleshooting of wafer processing flaws.
Based on the above, it can be appreciated that there presently exists a need for a method for determining the original location of a semiconductor chip on a wafer on which it was fabricated, after the chip is separated from the wafer. The present invention fulfills this need.